Question

What is the measure of ∠T, rounded to the nearest degree?

Answer 1

In this question, we use law of cosine which is

$RS^2 = RT^2 + ST^2 -2(RT)(ST) cos T$

Substituting the given values of RS,RT, ST , we will get

$3^2 = 5^2 + 7^2 -2(5)(7) cos T \\ 9 = 25 +49 - 70 cos T$

$cos T = \frac{65}{70}$

Taking inverse cosine on both sides

$T = cos^{-1} ( \frac{65}{70})$

$T = 22$

Answer 2

Cosine theorem
3²=5²+7²-2*5*7*cosT
9=25+49-70*cosT
9-74=-70 *cos T
-65/(-70)= cos T
T = arccos (65/70)≈22°